﻿THE 
  TERTIARY 
  FORMATIONS 
  OF 
  VIRGINIA. 
  331 
  

  

  The 
  total 
  number 
  of 
  species 
  of 
  shells 
  from 
  these 
  points 
  which 
  have 
  

   yet 
  been 
  identified 
  is 
  about 
  ninety-six, 
  to 
  which 
  we 
  will 
  now 
  add 
  the 
  

   following 
  new 
  species, 
  recently 
  discovered 
  by 
  ourselves. 
  To 
  this 
  list 
  

   others 
  believed 
  to 
  be 
  new, 
  and 
  at 
  present 
  under 
  examination, 
  will 
  here- 
  

   after 
  be 
  added. 
  

  

  • 
  

  

  II. 
  DESCRIPTION 
  OF 
  SOME 
  NEW 
  MIOCENE 
  FOSSIL 
  SHELLS. 
  

  

  Turritella 
  ter-striata. 
  C 
  

  

  23. 
  Whorls 
  strongly 
  angulated 
  by 
  three 
  principal 
  revolving 
  elevated 
  

   spiral 
  ridges 
  ; 
  the 
  lowest, 
  being 
  about 
  one-third 
  from 
  the 
  base, 
  is 
  the 
  

   most 
  prominent 
  ; 
  the 
  second, 
  which 
  closely 
  adjoins 
  and 
  almost 
  coal- 
  

   esces 
  with 
  the 
  first, 
  is 
  much 
  feebler 
  ; 
  the 
  third, 
  which 
  is 
  nearly 
  one- 
  

   third 
  the 
  height 
  of 
  the 
  whorl 
  from 
  the 
  summit, 
  is 
  more 
  distinct 
  and 
  is 
  

   separated 
  from 
  the 
  second 
  by 
  a 
  deep 
  and 
  wide 
  channel 
  ; 
  next 
  the 
  base 
  

   of 
  each 
  whorl 
  are 
  three 
  fine 
  spiral 
  striae 
  ; 
  others, 
  to 
  the 
  number 
  of 
  four 
  

   or 
  five, 
  occupy 
  the 
  space 
  between 
  the 
  principal 
  ridge 
  and 
  the 
  summit 
  ; 
  

   crossing 
  these 
  are 
  very 
  fine 
  indistinct 
  transverse 
  arcuated 
  wrinkles. 
  

  

  This 
  shell 
  is 
  obviously 
  distinct 
  from 
  the 
  variabilis 
  in 
  the 
  great 
  ine- 
  

   quality 
  of 
  the 
  three 
  principal 
  ridges, 
  the 
  depth 
  of 
  the 
  central 
  channel, 
  

   and 
  the 
  greater 
  delicacy 
  of 
  the 
  transverse 
  wrinkles. 
  

  

  Locality, 
  vicinity 
  of 
  Williamsburg 
  ; 
  in 
  the 
  Miocene 
  shell 
  marl. 
  

   Length, 
  about 
  two 
  inches. 
  

  

  Turritella 
  quadri-striata. 
  

  

  24. 
  Shell 
  turrited, 
  regularly 
  conical 
  : 
  whorls 
  flattened, 
  with 
  four 
  

   principal 
  revolving 
  equidistant 
  spiral 
  striae 
  ; 
  a 
  fifth, 
  less 
  conspicuous, 
  

   bounds 
  the 
  base 
  of 
  the 
  whorl 
  ; 
  the 
  whole 
  of 
  these 
  are 
  alternated 
  with 
  

   five 
  much 
  smaller 
  interposed 
  striae 
  ; 
  near 
  the 
  summit 
  of 
  the 
  whorls 
  are 
  

   traces 
  of 
  others 
  yet 
  more 
  delicate 
  : 
  five 
  transverse 
  arcuated 
  wrinkles, 
  

   not 
  very 
  distinct. 
  

  

  Locality, 
  Williamsburg, 
  as 
  before 
  ; 
  length, 
  one 
  inch. 
  This 
  shell 
  

   diners 
  from 
  the 
  variabilis 
  in 
  the 
  flatness 
  of 
  the 
  whorls, 
  and 
  the 
  number 
  

   and 
  relative 
  proportion 
  of 
  the 
  principal 
  striae 
  ; 
  it 
  is 
  also 
  a 
  much 
  more 
  

   delicate 
  and 
  smaller 
  shell. 
  

  

  